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Abstract
This article reviews the scope of inorganic cluster compounds interrogated in single-molecule break-junction measurements. This body of work lies at the intersection between the fields of inorganic cluster chemistry and single-molecule electronics, where discrete inorganic cluster molecules are used as the active components in molecular electronic circuitry. We explore the breadth of transition metal and main group cluster compounds that have been studied in single-cluster junctions, largely within the context of scanning tunnelling microscopy break-junction (STM-BJ) measurements. Our discussion centers on how the structure and bonding of inorganic cluster compounds give rise to desirable quantum transport effects such as room-temperature current blockade, sequential tunneling, voltage-gated conductance switching, destructive quantum interference, and high thermoelectric currents.
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Affiliation(s)
- Timothy C Siu
- Department of Chemistry, University of California, Riverside, CA 92521, USA.
| | - Joshua Y Wong
- Department of Chemistry, University of California, Riverside, CA 92521, USA.
| | - Matthew O Hight
- Department of Chemistry, University of California, Riverside, CA 92521, USA.
| | - Timothy A Su
- Department of Chemistry, University of California, Riverside, CA 92521, USA. and Materials Science and Engineering Program, University of California, Riverside, CA 92521, USA
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Kanazawa Y, Tsuji H, Ehara M, Fukuda R, Casher DL, Tamao K, Nakatsuji H, Michl J. Electronic Transitions in Conformationally Controlled Peralkylated Hexasilanes. Chemphyschem 2016; 17:3010-3022. [DOI: 10.1002/cphc.201600633] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Indexed: 11/08/2022]
Affiliation(s)
- Yuki Kanazawa
- SOKENDAI The Graduate University for Advanced Studies, Nishigonaka, Myodaiji Okazaki 444–8585 Japan
- Institute for Molecular Science and Research Center for Computational Science, Nishigonaka, Myodaiji Okazaki 444–8585 Japan
| | - Hayato Tsuji
- International Research Center for Elements Science (IRCELS) Institute for Chemical Research Kyoto University, Uji Kyoto 611-0011 Japan
- Department of Chemistry Faculty of Science Kanagawa University 2946 Tsuchiya Hiratsuka Kanagawa 259–1293 Japan
| | - Masahiro Ehara
- SOKENDAI The Graduate University for Advanced Studies, Nishigonaka, Myodaiji Okazaki 444–8585 Japan
- Institute for Molecular Science and Research Center for Computational Science, Nishigonaka, Myodaiji Okazaki 444–8585 Japan
- Elements Strategy Initiative for Catalysts and Batteries (ESICB) Kyoto University Kyoto 615–8520 Japan
| | - Ryoichi Fukuda
- Elements Strategy Initiative for Catalysts and Batteries (ESICB) Kyoto University Kyoto 615–8520 Japan
| | - Deborah L. Casher
- Department of Chemistry and Biochemistry University of Colorado at Boulder Boulder Colorado 80309-0215 USA
| | - Kohei Tamao
- International Research Center for Elements Science (IRCELS) Institute for Chemical Research Kyoto University, Uji Kyoto 611-0011 Japan
- RIKEN 2-1 Hirosawa Saitama 351-0198 Japan
| | - Hiroshi Nakatsuji
- Quantum Chemistry Research Institute Goryo Oohara 1–36, Nishikyo-ku Kyoto 615–8245 Japan
| | - Josef Michl
- Department of Chemistry and Biochemistry University of Colorado at Boulder Boulder Colorado 80309-0215 USA
- Institute of Organic Chemistry and Biochemistry Academy of Sciences of the Czech Republic Flemingovo nám. 2 16610 Prague Czech Republic
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Tsuji H, Fogarty HA, Ehara M, Fukuda R, Casher DL, Tamao K, Nakatsuji H, Michl J. Electronic transitions in conformationally controlled tetrasilanes with a wide range of SiSiSiSi dihedral angles. Chemistry 2014; 20:9431-41. [PMID: 25043859 DOI: 10.1002/chem.201403495] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Indexed: 11/08/2022]
Abstract
Unlike π-electron chromophores, the peralkylated n-tetrasilane σ-electron chromophore resembles a chameleon in that its electronic spectrum changes dramatically as its silicon backbone is twisted almost effortlessly from the syn to the anti conformation (changing the SiSiSiSi dihedral angle ω from 0 to 180°). A combination of UV absorption, magnetic circular dichroism (MCD), and linear dichroism (LD) spectroscopy on conformationally controlled tetrasilanes 1-9, which cover fairly evenly the full range of angles ω, permitted a construction of an experimental correlation diagram for three to four lowest valence electronic states. The free chain tetrasilane n-Si4 Me10 (10), normally present as a mixture of three enantiomeric conformer pairs of widely different angles ω, has also been included in our study. The spectral trends are interpreted in terms of avoided crossings of 1B with 2B and 2A with 3A states, in agreement with SAC-CI calculations on the excited states of 1-7 and conformers of 10.
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Affiliation(s)
- Hayato Tsuji
- International Research Center for Elements Science (IRCELS), Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011 (Japan); Present address: Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku,Tokyo 113-0033 (Japan)
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Tachikawa H. Mechanism of Electron and Hole Localization in Poly(dimethylsilane) Radical Ions. J Phys Chem A 2007; 111:10134-8. [PMID: 17880048 DOI: 10.1021/jp072630u] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The mechanism of excess electron and hole localizations in radical ions of poly(dimethylsilane) (PDMS) has been investigated by means of molecular dynamics (MD) and extended Hückel methods. Oligo(dimethylsilane) composed of 100 monomer units of dimethylsilane, CH3(Si(CH3)2)(n)CH3 (n = 100), were used as a model of PDMS. Both wings of the oligomer were capped by a methyl group. First, the geometry of PDMS with a regular all-trans form was fully optimized by MM2+ energy gradient method. Next, the MD calculation was carried out for PDMS at 300 K. The structure of PDMS was gradually deformed as a function of simulation time, especially the dihedral angle of Si-Si-Si-Si backbone that was randomized. At time zero when the structure has the regular all-trans form, both the excess electron and hole were completely delocalized on the Si backbone of PDMS. After thermal activation, the localization of the electron and hole was found. The mechanism of the localization was discussed on the basis of theoretical results.
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Affiliation(s)
- Hiroto Tachikawa
- Division of Materials Chemistry, Graduate School of Engineering, Hokkaido University, Sapporo 060-8628, Japan. hiroto@eng. hokudai.ac.jp
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Sandström N, Piqueras MC, Ottosson H, Crespo R. Electronic excitations of 1,4-disilyl-substituted 1,4-disilabicycloalkanes: a MS-CASPT2 study of the influence of cage size. J Phys Chem A 2007; 111:2804-10. [PMID: 17388376 DOI: 10.1021/jp070010n] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We present a multistate complete active space second-order perturbation theory computational study aimed to predict the low-lying electronic excitations of four compounds that can be viewed as two disilane units connected through alkane bridges in a bicyclic cage. The analysis has focused on 1,4-disilyl-1,4-disilabicyclo[2.2.1]heptane (1a), 1,4-bis(trimethylsilyl)-1,4-disilabicyclo[2.2.1]heptane (1b), 1,4-disilyl-1,4-disilabicyclo[2.1.1]hexane (2a), and 1,4-bis(trimethylsilyl)-1,4-disilabicyclo[2.1.1]hexane (2b). The aim has been to find out the nature of the lowest excitations with significant oscillator strengths and to investigate how the cage size affects the excitation energies and the strengths of the transitions. Two different substituents on the terminal silicon atoms (H and CH3) were used in order to investigate the end group effects. The calculations show that the lowest allowed excitations are of the same character as that found in disilanes but now red-shifted. As the cage size is reduced from a 1,4-disilabicyclo[2.2.1]heptane to a 1,4-disilabicyclo[2.1.1]hexane, the Si...Si through-space distance decreases from approximately 2.70 to 2.50 A and the lowest allowed transitions are red-shifted by up to 0.9 eV, indicating increased interaction between the two Si-Si bonds. The first ionization potential, which corresponds to ionization from the Si-Si sigma orbitals, is lower in 1b and 2b than in Si2Me6 by approximately 0.9 and 1.2 eV, respectively. Moreover, 1b and 2b, which have methyl substituents at the terminal Si atoms, have slightly lower excitation energies than the analogous species 1a and 2a.
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Affiliation(s)
- Niclas Sandström
- Department of Biochemistry and Organic Chemistry, Box 576, Uppsala University, 751 23 Uppsala, Sweden
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The electronic structures of all trans form of permethyl-oligosilane radical cation with longer chain: A density functional theory study. J Organomet Chem 2006. [DOI: 10.1016/j.jorganchem.2006.08.090] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Fogarty HA, Ottosson H, Michl J. Calculation of Relative Energies of Permethylated Oligosilane Conformers in Vapor and in Alkane Solution. J Phys Chem B 2006; 110:25485-95. [PMID: 17165997 DOI: 10.1021/jp064643y] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The geometries of 35 conformers of Me(SiMe2)nMe (n = 4, 1; n = 5, 2; n = 6, 3; n = 7, 4) were optimized at the MP2/VTDZ level, and CCSD(T) single-point calculations were done at three MP2/VTDZ conformer geometries of 1. The relative ground-state energies of the conformers of 1-4 in the gas phase were obtained from the MP2/VTDZ electronic energy, zero-point vibrational energy, and thermal corrections at 0, 77, and 298 K. Relative energies in an alkane solvent at 77 and 298 K were obtained by the addition of solvation energies, obtained from the SM5.42R model. The calculated energies of 26 of the conformers (n = 4-6) have been least-squares fitted to a set of 15 additive increments associated with each Si-Si bond conformation and each pair of adjacent bond conformations, with mean deviations of 0.06-0.20 kcal/mol. An even better fit for the energies of 24 conformers (mean deviations, 0.01-0.09 kcal/mol) has been obtained with a larger set of 19 increments, which also contained contributions from selected combinations of conformations of three adjacent bonds. The utility of the additive increments for the prediction of relative conformer energies in the gas phase and in solution has been tested on the remaining nine conformers (n = 6, 7). With the improved increment set, the average deviation from the SM5.42R//MP2 results for solvated conformers at 298 K was 0.18 kcal/mol, and the maximum error was 0.98 kcal/mol.
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Affiliation(s)
- Heather A Fogarty
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215, USA
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Tachikawa H, Kawabata H. Structures and Electronic States of Permethyloligosilane Radical Ions with All-Trans Form Sin(CH3)2n+2± (n = 2−6): A Density Functional Theory Study. J Chem Theory Comput 2006; 3:184-93. [DOI: 10.1021/ct600163r] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Hiroto Tachikawa
- Division of Molecular Chemistry, Graduate School of Engineering, Hokkaido University, Sapporo 060−8628, Japan
| | - Hiroshi Kawabata
- Venture Business Laboratory, Kyoto University, Kyoto 606−8501, Japan
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Fogarty HA, Imhof R, Michl J. Magnetic circular dichroism of peralkylated tetrasilane conformers. Proc Natl Acad Sci U S A 2004; 101:10517-22. [PMID: 15249672 PMCID: PMC489969 DOI: 10.1073/pnas.0403209101] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Magnetic circular dichroism (MCD) of five peralkylated tetrasilanes (1-5) conformationally constrained to angles ranging from nearly 0 degrees to 180 degrees and of the open chain tetrasilane Si(4)Me(10) (6) shows a clear conformational dependence and permits the detection of previously hidden transitions. In the tetrasilane CH(2)Si(4)Me(8) (1), with the smallest dihedral angle, comparison of MCD with absorption spectra reveals four low-energy electronic transitions. In the tetrasilanes 2-4, three distinct transitions are apparent. In tetrasilanes 5 and 6, MCD reveals the very weak transition that has been predicted to be buried under the first intense peak and to which the anomalous thermochromism of 6 and other short-chain oligosilanes has been attributed.
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Affiliation(s)
- Heather A Fogarty
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309-0215, USA
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Motonaga M, Nakashima H, Katz S, Berry DH, Imase T, Kawauchi S, Watanabe J, Fujiki M, Koe JR. The first optically active polygermanes: preferential screw sense helicity of enantiopure chiral-substituted aryl polygermanes and comparison with analogous polysilanes. J Organomet Chem 2003. [DOI: 10.1016/s0022-328x(03)00236-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Sasanuma Y, Kato H, Kaito A. Conformational Analysis of Poly(di-n-butylsilane), Poly(di-n-hexylsilane), and Poly(methyl-n-propylsilane) by a Rotational Isomeric State Scheme with Molecular Dynamics Simulations. J Phys Chem B 2003. [DOI: 10.1021/jp030681v] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Yuji Sasanuma
- Department of Materials Technology, Faculty of Engineering, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan, and Macromolecular Technology Research Center, National Institute of Advanced Industrial Science and Technology (AIST), AIST Tokyo Water Front, 2-41-6 Aomi, Kohtoh-ku, Tokyo 135-0064, Japan
| | - Haruhisa Kato
- Department of Materials Technology, Faculty of Engineering, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan, and Macromolecular Technology Research Center, National Institute of Advanced Industrial Science and Technology (AIST), AIST Tokyo Water Front, 2-41-6 Aomi, Kohtoh-ku, Tokyo 135-0064, Japan
| | - Akira Kaito
- Department of Materials Technology, Faculty of Engineering, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan, and Macromolecular Technology Research Center, National Institute of Advanced Industrial Science and Technology (AIST), AIST Tokyo Water Front, 2-41-6 Aomi, Kohtoh-ku, Tokyo 135-0064, Japan
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Winokur MJ, West R. X-ray Diffraction and Molecular Modeling Studies of Poly(di-n-alkylsilanes): The Near Planar Type Phases of Poly(di-n-butylsilane) and Poly(di-n-hexylsilane). Macromolecules 2003. [DOI: 10.1021/ma026017e] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- M. J. Winokur
- Department of Physics, University of Wisconsin, Madison, Wisconsin 53706, and Organosilicon Research Center, Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706
| | - R. West
- Department of Physics, University of Wisconsin, Madison, Wisconsin 53706, and Organosilicon Research Center, Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706
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Piqueras MC, Crespo R, Michl J. The Transoid, Ortho, and Gauche Conformers of Decamethyl-n-tetrasilane, n-Si4Me10: Electronic Transitions in the Multistate Complete Active Space Second-Order Perturbation Theory Description. J Phys Chem A 2003. [DOI: 10.1021/jp022675p] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Mari Carmen Piqueras
- Departament de Química Física i Institut de Ciència Molecular, Universitat de València, Dr. Moliner 50, E-46100 Burjassot (Valencia), Spain
| | - Raül Crespo
- Departament de Química Física i Institut de Ciència Molecular, Universitat de València, Dr. Moliner 50, E-46100 Burjassot (Valencia), Spain
| | - Josef Michl
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215
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Rooklin DW, Schepers T, Raymond-Johansson MK, Michl J. Time-dependent density functional theory treatment of the first UV absorption band in all-transoid permethyloligosilanes SinMe2n + 2 (n = 2-8, 10). Photochem Photobiol Sci 2003; 2:511-7. [PMID: 12803073 DOI: 10.1039/b302087h] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The TD B3LYP/6-311G(d,p) method slightly overestimates the excitation energies of the first UV absorption band of the all-transoid conformers of SinMe2n + 2 (n = 2-8, 10), deduced from temperature-dependent measurements on conformer mixtures in hydrocarbon solvents, by a nearly constant amount (approximately 2000 cm-1). The TD B3LYP/6-31G(d) results are less satisfactory. The first band is calculated to be due to a sigma pi * excitation in Si2Me6 and to a superposition of overlapping sigma sigma * and sigma pi * excitations in the longer oligosilanes. The sigma pi * excitation is calculated to lie a little below the sigma sigma * excitation up to Si4Me10, the two transitions are nearly degenerate in Si5Me12, and the sigma sigma * excitation drops increasingly below the sigma pi * as the chain length is extended. The dipole strength of the sigma sigma * excitation grows by 4.8 D2 (D = debye) per added SiSi bond (more slowly up to n = 5) and the calculation overestimates it by a factor of about three. The sigma pi * excitation is computed to carry no or almost no oscillator strength, but as noted earlier by others, its presence is critical for the interpretation of the observed thermochromism. Upon cooling below room temperature, the first absorption maximum is blue-shifted in short chains and red-shifted in long chains. Unlike the prior investigators, we attribute the blue shift to the disappearance of hot bands built on the sigma pi * origin using intensity borrowing sigma-pi mixing vibrations (b1 in Si3Me8). As usual, the red shift is attributed to the disappearance of twisted conformers, which have higher calculated sigma sigma * excitation energies.
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Affiliation(s)
- David W Rooklin
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309-0215, USA
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Fujiki M, Koe JR, Terao K, Sato T, Teramoto A, Watanabe J. Optically Active Polysilanes. Ten Years of Progress and New Polymer Twist for Nanoscience and Nanotechnology. Polym J 2003. [DOI: 10.1295/polymj.35.297] [Citation(s) in RCA: 135] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Schepers T, Michl J. Optimized ladder C and ladder H models for sigma conjugation: chain segmentation in polysilanes. J PHYS ORG CHEM 2002. [DOI: 10.1002/poc.527] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Ichino Y, Minami N. Time-resolved fluorescence study of isolated and aggregated permethyldecasilanes. Chem Phys Lett 2001. [DOI: 10.1016/s0009-2614(01)00769-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Tsuji H, Toshimitsu A, Tamao K, Michl J. UV, MCD, and LD Spectra of a Conformationally Constrained ortho-Tetrasilane: Support for the Avoided Crossing Model of Conformational Effects on Excited States. J Phys Chem A 2001. [DOI: 10.1021/jp010792z] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Hayato Tsuji
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Akio Toshimitsu
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Kohei Tamao
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Josef Michl
- Department of Chemistry and Biochemistry, University of Colorado at Boulder, Boulder, Colorado 80309-0215
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Ichino Y, Minami N. Annealing-Induced Molecular Reorientation in Oligosilane Thin Films. J Phys Chem B 2001. [DOI: 10.1021/jp003544w] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Yoshiro Ichino
- National Institute of Materials and Chemical Research, 1-1 Higashi, Tsukuba 305-8565, Japan
| | - Nobutsugu Minami
- National Institute of Materials and Chemical Research, 1-1 Higashi, Tsukuba 305-8565, Japan
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Crespo R, Merchán M, Michl J. Electronic Excitation in a Saturated Chain: An MS-CASPT2 Treatment of the Anti Conformer of n-Tetrasilane. J Phys Chem A 2000. [DOI: 10.1021/jp001973o] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Raül Crespo
- Departament de Química Física, Universitat de València, Dr. Moliner 50, Burjassot, E-46100 València, Spain
| | - Manuela Merchán
- Departament de Química Física, Universitat de València, Dr. Moliner 50, Burjassot, E-46100 València, Spain
| | - Josef Michl
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215
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